>> Friday, January 18, 2013

As always after a snow event, some folks wind up doing well in the snow department while others don't. That was definitely the case with this system.

I am still compiling snow reports as of this typing, but I am pretty pleased with my snowfall forecast for the Triad area and points north into southern Virginia. Many, many spots, especially around the Triad, had some intense periods of thundersnow, which is always really neat to experience. All in all, most snow totals fell in line with the ranges I had outlined in this area.

However, I am disappointed in how the forecast for the Charlotte area and back into the southern mountains to around Asheville turned out. This is the portion of the forecast that did not go overly well. For the Charlotte area, I had gone with 1-4", and in many spots, that simply didn't happen....the changeover to snow from rain was too late to put snow on the ground in many instances in that region.

For the disappointed snow fans around the region, I am sorry it didn't work out this time. As always, I will look at what worked and what didn't work with the forecast, see what can be learned, and move forward.

To me, the first warning shots to be fired were the RPM modeling yesterday afternoon. After laying down some impressive snow totals with its morning runs yesterday, as the day wore on, the changeover from rain to snow got later and later with each subsequent run. The trend being indicated on the RPM turned out to be real for the southern piedmont, and the result was a lack of accumulating snow in the southern portions of NC, some of the southern mountains, and the Upstate.

Moving forward, we will get something we have not had a lot of recently..... sunshine. In fact, each day today through much of next week should feature a good deal of sun.

It still appears a good blast of arctic air should arrive by Tuesday next week. Some piedmont spots (mainly in northern NC) might not get above freezing for highs Tuesday. Lows by Wednesday should be in the teens for most.

Here's today's video.... a look at the previous system and a look ahead...

>> Thursday, January 17, 2013

The overnight modeling basically held serve with our incoming system. Some bullet-points....

Rain today...and it will be heavy at times. Many foothill and piedmont spots will pick up at least and inch of rain.... maybe 2"

As colder temperatures aloft move in as the upper level system strengthens, the rain will switch to a heavy wet snow from northwest to southeast. That changeover will begin this afternoon in the mountains, probably 6-8pm for the Triad, and a little bit later for Charlotte and RDU.

The snow will not last terribly long. However, it's going to be quite heavy while it is falling. Snow rates will likely be quite impressive in some areas, and there could even be some thundersnow, one of my favorite weather phenomena.

This heavy, wet snow will likely bring down form trees and powerlines in the spots with heavier accumulations.

Temperatures will drop into the 20s by late tonight in many spots. I expect many area roadways to be quite treacherous as the evening and night unfold.

A Winter Storm Warning is up for much of the region:

Below is my accumulation map....as always, there will be localized variabilities. This is a little lower than normal confidence snow forecast due to initially warm, wet ground conditions as well as the chances of some heavy rates of snow. There is bust potential, both high and low, all over the place.

>> Wednesday, January 16, 2013

All in all, no huge surprises with the 12z suite of model guidance. No reason at this point for me to change the accumulation ideas I put out this morning. Like I mentioned this morning, I will put out my final map tomorrow morning. It will be at that point that, if need be, I will up totals for some areas.

The 12z NAM was once again intense and was healthy with the NC snow amounts. The European model also put down some nice amounts as well for much of NC.

There's our upper air low in Texas:

North trend?? For those in NC and northern SC, that is that last thing you want if you are wanting snow. There is some subtropical ridging near the Bahamas that the models continue to get a handle on, and it is possible that our system could trend a little farther north.

That is a concern in the back of my mind. However, I think with the the polar vortex sitting where it is, as well as the trough position in the eastern US, there is only so far north this can go.

The duration of snow with this one will be relatively brief, but quite intense. But while it's snowing, it could be a very heavy, wet snow.

There are some similarities in this system to the early March 2009 system. However, this system isn't quite as strong or cold, but it is in the ballpark if the stronger modeling is correct.

I do not think the snow will be as extensive or will the totals be as significant as they were over a wide area with that system. However, much like in that system, rain will fall leading up to the kick over to snow, and the rain will be heavy at times. Then, as colder air aloft crashes into the system, rain will kick over to snow from northwest to southeast, likely in the mountains and northern foothills first.

At that point, as the deformation band pivots through, a period of heavy snow is possible, especially for the mountains, foothills, and locations roughly near and north of I-40 up into Virginia.

Southern Piedmont and even northern Upstate snow fans do have a chance....but it will depend on how the cold air as well as that deformation band behave.

This is a dynamic system, and changes are likely. But that's how I see it as of now.

Below the video is my discussion, and I run down all of the modeling and give my thoughts on the snow potential later tomorrow and tomorrow night in today's video. Please give it a look....

Discussion:

First of all, more rain at times today, and then our next system spreads another shield of rain in by later tonight.

First things first, we will see a soaking rain for much of the region tomorrow...some folks could easily eclipse 1" or even 2" of rain.

This is a powerful upper air low pressure area that will be weakening as it pulls into the Carolinas. I suggested in my videos earlier this week that the models might trend this system stronger and stronger as they got a better handle on it, and they have done just that.

As that upper air low pulls in, it will draw in colder air aloft from the north, and then as you have heavy precipitation, it will pull that cold air down toward the ground from above. That's called dynamic cooling.

In a situation like this, the line is always razor-thin between moderate to heavy rain and moderate to heavy snow....and it can kick back and forth dependent on precipitation rates.

But with all of that said, I think many spots in NC and some spots in northern SC will see the rain end as at least a brief period of snow.

Now, the ground is quite warm with all of the recent warmth, so it will take some effort to get snow accumulations. However, with that said, I do think some of us will see some snow on the ground.

This is a little earlier in the game than I normally like to do it, but here is my VERY preliminary snowfall map. This is 100% subject to change, and I will put out my final map tomorrow morning.

>> Tuesday, January 15, 2013

Please take time to see today's video... I spend a large chunk of time discussing our Thursday/ Thursday night system.

At the moment, I do think the system (mainly rain for the Piedmont) could END as some snow in parts of the Piedmont, but I think it would be more in the 'novelty' category as opposed to anything significant. But there are still question marks....

The system simply has a couple of things working against it in terms of getting snow on the ground in the Piedmont, including time of day (now more daytime than night) as well as warm ground temps. But we will see.

But this is a classic case of the models seeing the 500mb disturbance better with each run, and therefore, you are seeing the system get stronger with each additional run. So we will see if that trend continues. If it does, somebody could get a surprise somewhere.

The potential is definitely there for more significant snows in the mountains (and maybe a few foothills areas??)....